This invention relates to a ball cock assembly having a novel combined volume control and anti-siphon feature integrated with the discharge portion of the valve assembly. Ball cock assemblies of the type under discussion here are employed to fill the flush tank of toilets. The service is demanding in that the valve must be designed to operate over long periods of time yet be capable of a positive shutoff after each operation to prevent water wastage. Superimposed on the above basic design criteria is the need to achieve a relatively quiet operation and the need to prevent any backflow of tank water into the supply line under water supply failure conditions.
Noise has always been a problem associated with the filling of the flush tank. The noise comes from three main sources (1) noise generated by the water turbulating around the valve seat and restrictions in the exit port; (2) noise generated by water splashing into the flush tank; and (3) noise generated by a heavy water flow in the supply piping itself. Some noise reduction has been achieved by the use of a hush tube which conducts the water discharged by the valve to the bottom of the flush tank. In this manner the outlet of the hush tube is submerged under water eliminating splashing noise and at the same time muffling some of the noise generated at the valve. While the hush tube has been partially effective, noise generation still remains a problem, particularly at higher water pressure.
The use of a hush tube has created a secondary problem in that the discharge outlet has been located below the water level in the flush tank, and if a negative pressure develops in the water supply line contaminated tank water can be drawn into the water supply. Plumbing codes recognize this hazard and require that an anti-siphon feature be designed into the valve so that under conditions of negative pressure in the supply line the inlet of the hush tube is exposed to atmospheric pressure. The anti-siphon feature takes the form of a vacuum break device situated between the outlet of the ball cock and the inlet to the hush tube.
There is a large body of art directed to ball cocks with an anti-siphon feature as typified by U.S. Pat. No. 2,777,460, issued Jan. 15, 1957 to Bennett Svirsky; U.S. Pat. No. 2,941,542, issued June 21, 1960 to David I. Jacobson and U.S. Pat. No. 3,171,424, issued Mar. 2, 1965 to Harold Shames et al. The patent to Svirsky shows an anti-siphon valve located between the fill valve and the top of a hush tube. Under conditions of zero or negative pressure the anti-siphon valve vents the hush tube to atmospheric pressure. Jacobson shows an anti-siphon ball valve movable to a first position connecting the fill valve to the hush tube and to a second position venting the hush tube to atmospheric air when the pressure in the supply line goes zero or negative. Shames et al show an anti-siphon disc valve movable to a first sealing position to provide a direct passage from the fill valve to the hush tube and to a second position to vent the hush tube to atmospheric pressure.
While the above mentioned patents do show ball cocks with an anti-siphon valve to vent the hush tube to atmospheric air under conditions of negative pressure, the prior art does not teach a combined anti-siphon valve and volume control.